💡 Intuition

• As we scan the array, we trade extra memory for speed by remembering past numbers, allowing us to instantly check whether the current number completes a valid pair. Eg target − currentNumber should exist in past numbers.
• We can maintain a hashmap to keep track of past number while iterating.

🚀 Solution

func twoSum(nums []int, target int) []int {
    hashmap := map[int]int{};

    for index,val := range nums {
		difference := target - val;

		if  indx,ok := hashmap[val]; ok  {
			return []int {
				indx,
				index,
			};
		}

		hashmap[difference] = index;
    }

	return []int {
		0,
		1,
	}
}

⏳ Time Complexity

• Since we are taking single loop for the array of length n, the time complexity will be O(n)